A genetic biomarker study to measure underreporting of needle and syringe sharing among people who inject drugs in Kermanshah, Iran

Background and Objective: Previous research has argued that needleand syringe sharing is under-reported by people who inject drugs(PWID). We aimed to measure under-reporting bias in needle andsyringe sharing using a genetic biomarker assay.Materials and Methods: Using convenience sampling data on selfreportof needle and syringe sharing for 320 PWID in Kermanshah, werecompared with results from genetic biomarkers to detect sharing. Thequestionnaire included items on socio-demographic characteristics, druguse, and HIV risk behaviors in the 30 days preceding the interview. Wealso reported the true and observed prevalence of needle sharing asmeasured by genetic biomarker and self-report. Finally we used logisticmodel regression to identify factors associated with under-reporting.Findings: Participants ranged in age from 18 to 54 years, mean = 27years; SD = 7.6 years. The mean, SD and median durations of injectiondrug use were 5.0 ± 4.2 and 4.1 (IQR, 3.3–11.5). Using the geneticbiomarker, out of the 320 PWID, 95 persons (29.7%, 95% CI 24.7- 35.0)have shared syringes and needles. Interestingly, self-reported HIVpositive PWID were more likely to under-report needle and syringesharing compared with those PWID who reported being HIVseronegative(AOR=1.8 ; 95% CI:1.06- 4.3; p-value= 0.02).Conclusions: HIV positive PWID were more likely to under-reportneedle and syringe sharing compared with HIV negative PWID. Thesefindings have important implications for future risk behavior studiesespecially those evaluating NSP effectiveness in BBV prevention.